By putting the silkworms on a modified diet, scientists have succeeded in producing coloured silk, which may help in removing the environmental hazards caused by dyeing of the fibre, according to the scientific journal Nature India.

The ‘green’ method developed by researchers at the National Chemical Laboratory (NCL) in Pune and Central Sericultural Research and Training Institute in Mysore enables the silkworms to directly produce coloured silk.

“The technique involves feeding the larvae their favourite food — mulberry leaves — dipped in dye. The dye is transported along the biochemical pathways of the silkworm to produce a coloured cocoon and coloured silk fibre,” says Nature India.

According to the journal commercial silk fibre produced by mulberry silkworm is generally white.

The modern textile industry demands that silk fibre be dyed into a variety of colours that can be weaved into attractive textiles.

But dyeing is one of the most polluting industries.

It requires huge quantities of water for bleaching, washing and rinsing, resulting in untreated wastewater laced with harmful toxins that get into canals and rivers.

Sayam Sengupta, one of the authors from NCL, said they investigated a series of dyes that could produce coloured silk in several shades. “Of course, many things need to work out to make it a successful technology — the dyes need to be non-toxic, they should preferentially color the fibroin and the color fastness properties need to match the color silk produced by traditional dyeing,” he said.

Also, the economics needs to work out in favour of the process. “If all of these are successful, this could prove to be a process that can eliminate dyeing of silk, which is known to be a polluting technology,” Sengupta said.